Impact of Frost on the Morphology and Chemical Composition of cv. Santulhana Olives

Abstract

Frost events and extreme weather phenomena greatly affect several characteristics of the olive fruit. This study evaluated the impact of frost on the morphology, composition (moisture, fat, fatty acids, tocopherols, and total phenolic contents), and antioxidant activity of olives of cv. Santulhana. A total of 14 trees from the same geographical region (Santulhão, northeast of Portugal) were chosen, including trees subjected or not subjected to frost conditions (n = 7 each). The results showed that frost led to morphological changes in olive fruits, particularly in terms of weight and diameter, which were imposed by a huge decrease in the moisture content (−20%). Fat relative content increased as a consequence of the water loss (+29% in fresh pulp weight), with a slight reduction of the relative abundance of saturated fatty acids (−4%) and tocopherol contents in the fat (−17%). However, the total phenolic contents and antioxidant activity were severely affected (−70% and −42%, respectively), with potential consequences for the olive oil stability and sensorial attributes. Principal component analysis showed that both morphological and chemical parameters could be used as biomarkers to identify olives subjected or not subjected to frost. The overall negative impact of frost on the minor antioxidant contents of cv. Santulhana olives may anticipate a quality loss of olive oils extracted from olives affected by frost.